Technological processes mediated by microorganisms and enzymes are promising alternatives for treatment of recalcitrant residues. Keratinases hydrolyze keratin, the primary component of some wastes generated in many industrial activities. The present study was designed to evaluate strategies for obtaining keratinases produced by fungi using submerged fermentation and two residues as substrates, chicken feathers and swine hair. Two fungi isolated from feather residues showed potential for keratinase production, Fusarium oxysporum and Aspergillus sp. These were subjected to submerged fermentation using chicken feathers and swine hair prepared in three conditions (microbial concentration reduction, sterilization and hydrogen peroxide). The residual mass was quantified and tested for keratinase production. The most potent enzymatic extract was used in the precipitation technique with salts and organic solvents. The best results of enzymatic activity were obtained using F. oxysporum, on the 6thday of fermentation, obtaining 243.25 U mL −1 using sterilized swine hair as the substrate. Aspergillus sp. showed the highest keratinolytic activity on the 9thday, 113.50 U mL −1 using feathers as the substrate. The highest degradation percentage was 59.20% (w/w) in swine hair and the precipitation technique, with relative activities close to 50%. The results are promising for the application of residues and microorganisms in biotechnological processes of economic and environmental interest.
The present study was designed to evaluate the scaling process used to obtain fungi and enzymes from Trichoderma koningiopsis to produce bioherbicides with low levels of genotoxicity using a stirred-tank bioreactor. We measured fungal biomass and activities of enzymes (amylase, cellulase, lipase and peroxidase). Fermentative products were applied to weeds (Bidens pilosa and Euphorbia heterophylla), and the bioherbicide effect was evaluated. We found greater elevations of peroxidase and lipase activity in the scaled-up models than in those at small scale (0.15 L), even with less biomass, suggesting that the scaling was cost-beneficial in terms of enzymatic yield. Bioherbicide activity tests showed up to 100-80% phytotoxic effects on weeds that were resistant to synthetic herbicide. A genotoxicity study of the fermented extract performed in Allium cepa meristem cells showed low genotoxicity and no DNA damage. Our findings point to new perspectives regarding bioherbicides derived from fungal fermentation and enzyme yield technology, aimed at sustainable and ecofriendly agriculture.
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